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Abstract:

Disclosed herein is a cylindrical steam reformer, including a reforming
part, a combustion part, an internal heat exchange part, and a steam
generation part, which are integrally manufactured into a single reactor,
thus forming an optimal heat exchange network leading to optimal
performance of the individual parts. In addition, the steam reformer of
this invention is designed in a manner such that an upper reactor zone, a
middle reactor zone, and a lower reactor zone are removably connected so
as to easily supply a catalyst and increase durability, and therefore
such a reformer can be mounted in places which are small and require
stability, such as hydrogen stations.

Claims:

1. A cylindrical steam reformer having an integrated heat exchanger,
comprising a reactor, the reactor including:an upper reactor zone having
an internal heat exchange part;a middle reactor zone connected to the
upper reactor zone and having a combustion part, a steam generation part,
and a reforming part; anda lower reactor zone constituting a lower
surface of the middle reactor zone.

2. The reformer according to claim 1, wherein the upper reactor zone
comprises two flow paths for transferring feed/steam and reformate,
respectively, in which the two flow paths are adjacent to each other for
heat exchange therebetween and thus constitute the internal heat exchange
part capable of controlling a heat exchange area and gas flow by
adjusting a number and a structure of plates used for the heat exchange.

3. The reformer according to claim 1, wherein the combustion part
comprises:a burner for burning air/fuel supplied via an air/fuel inlet;a
first combustion gas flow path and a second combustion gas flow path
formed for surrounding the reforming part in order to exchange heat
between combustion gas produced in the burner and the reforming part;a
third combustion gas flow path for exchanging heat between the combustion
gas passed through the second combustion gas flow path and the steam
generation part; anda combustion exhaust gas outlet for externally
discharging the combustion gas passed through the third combustion gas
flow path.

4. The reformer according to claim 1, wherein the steam generation part
comprises:a steam inlet for externally supplying steam;a steam generation
path for exchanging heat between the steam supplied via the steam inlet
and the combustion gas passed through the third combustion gas flow path;
anda steam outlet for discharging the steam passed through the steam
generation path to the upper reactor zone.

5. The reformer according to claim 1, wherein the reforming part comprises
a high-temperature feed/steam path and a reforming path, as two flow
paths formed by a reforming separation pipe provided in a space defined
by the reforming pipe, and a high-temperature reformate discharge pipe,
in whichthe high-temperature feed/steam path functions to exchange heat
between the feed/steam, supplied after having passed through the internal
heat exchange part provided in the upper reactor zone, and the second
combustion gas flow path surrounding the reforming pipe, andthe reforming
path functions to convert the high-temperature feed/steam passed through
the high-temperature feed/steam path into reformate via a reforming
reaction.

6. The reformer according to claim 1, wherein the internal heat exchange
part and steam generation path of the steam generation part are filled
with porous metal filler in order to assure a maximum heat transfer area
for a minimum volume.

7. The reformer according to claim 6, wherein the filler comprises metal
having high corrosion resistance and is in mesh, fiber or knit form in
order to prevent pressure drop in a pipe.

8. The reformer according to claim 1, wherein the upper reactor zone, the
middle reactor zone, and the lower reactor zone are removably connected,
and a heat transfer path is formed in the upper reactor zone and the
middle reactor zone by connecting the upper reactor zone, the middle
reactor zone, and the lower reactor zone, thus alleviating an effect of
thermal expansion of metal on the reactor during rapid start-up
operation.

Description:

TECHNICAL FIELD

[0001]The present invention relates to a cylindrical steam reformer, which
can be applied to include fuel cells requiring hydrogen or hydrogen
stations for supplying hydrogen to fuel cell vehicles or other similar
places, so as to continuously supply hydrogen using natural gas or
hydrocarbons.

BACKGROUND ART

[0002]While problems of limitation of the amount of buried fossil fuel and
environmental contamination have occurred, a new era of hydrogen energy
using hydrogen, which is a harmless clean fuel as an energy source, is
predicted to come. However, there presently exist technical and
commercial limitations on producing hydrogen from alternative energy as
pure clean energy. Thus, hydrogen is intended to be produced as clean
fuel having little contamination using conventional fossil fuels, that
is, hydrocarbons including natural gas, as an intermediate step.

[0003]Such hydrogen has been already used in various industrial fields,
such as ammonia synthesis, methanol synthesis, petroleum refining
industries including hydrodesulfurization, hydro-treating, or general and
refined chemical processes, electronic and semiconductor industries, food
and metal processing, etc. In particular, in energy fields, the use of
hydrogen has broadened beyond use as a propellant in a space shuttle in
which it is difficult to implement an internal combustion engine, to
fuels for fuel cells and fuel cell vehicles for use in homes or power
plants capable of solving problems of self-supply of power, energy
efficiency, and environmental contamination.

[0004]To this end, methods of preparing hydrogen, which have been proposed
to date, include, for example, steam reforming of fossil fuel (coal,
petroleum, natural gas, propane, butane), partial oxidation or
autothermal reforming, electrolysis of water, etc. Of these methods, a
steam reforming process is regarded as a commercially and economically
usable technique.

[0005]The steam reforming process is mainly used for production of
hydrogen on a large scale. In such a case, a reforming reactor used for
the hydrogen production process is designed to be operated under
conditions of high pressure (15-25 bar) and high temperature (850°
C. or more), thus advantageously preparing hydrogen. However, the steam
reforming process suffers because the size of the reactor itself is very
large, and thus, a thermal network is difficult to effectively design,
resulting in very low efficiency. On the other hand, in the case where
the reforming reactor used for the hydrogen production process is
designed to have a small or medium size, the manufacture of such a
reactor is complicated and the installation cost thereof greatly
increases, therefore negating economic benefits.

[0006]In addition, when the device is designed to be large in terms of
stable operation, a reforming reactor, high-temperature and
low-temperature water-gas shift reactor, and a steam generator necessary
for respective unit processes should be separately mounted, and an
external heat exchanger for heat exchange of the above reactors should be
additionally provided, thereby enlarging the whole structure of the
device. Consequently, due to heat loss in the heat exchanger and the pipe
connected to each reactor, it is difficult to realize high heat
efficiency.

[0007]With the goal of overcoming such problems of small and medium sized
reformers, various thorough attempts have been made to partially combine
respective unit processes, develop a catalyst suitable for small and
medium sized systems, optimize a mutual heat exchange network through
heat flow analysis, simplify the structure of the reformer so as to
increase processibility and productivity, and integrate the reactors
while reducing the sizes thereof in order to decrease initial operation
time and heat loss, resulting in increased heat efficiency.

[0008]In this regard, a conventional small or medium sized reformer is
shown in FIG. 1. As shown in this drawing, the conventional reformer
requires installation of a large external heat exchanger to the outside
thereof so as to help increase the temperature of feed/steam to a
temperature (500-700° C.) appropriate for a steam reforming
reactor using high-temperature combustion exhaust gas discharged after
supplying heat of combustion gas produced in a burner to a reforming
reactor for a reforming reaction in the reforming reactor. In this case,
however, since the heat exchanger functions to exchange heat of the
combustion exhaust gas at 500° C. or more, it should be suitable
for use at high temperatures and should have a relatively large size,
causing problems related to cost and size. Particularly, the increase in
heat efficiency is limited, attributable to heat insulating problems of
the heat exchanger itself and the heat loss from pipes.

[0009]Further, in order to remove carbon monoxide from high-temperature
reformate, including reformed hydrogen, carbon monoxide and carbon
dioxide steam, when the reformate is supplied to the water-gas shift
reactor, another external heat exchanger should be additionally provided
to decrease the temperature of reformate to 400-500° C. to be
suitable for a high temperature shift reaction. As such, however, the
problem of material for the heat exchanger occurs, along with a problem
of heat transfer efficiency when using air, which is the fuel for the
burner, as the heat exchange medium, and thus it is difficult to minimize
the heat loss.

[0010]Accordingly, to solve the above problems, there is an urgent need
for a steam reformer capable of minimizing heat loss occurring in the
heat exchangers and pipes and optimizing the mounting space.

DISCLOSURE OF INVENTION

Technical Problem

[0011]Therefore, it is an object of the present invention to provide a
cylindrical steam reformer, comprising a reforming part, a combustion
part, an internal heat exchange part, and a steam generation part, which
are integrally manufactured into a single reactor, thus forming an
optimal heat exchange network leading to optimal performance of the
individual parts.

[0012]Another object of the present invention is to provide a cylindrical
steam reformer, in which an internal heat exchange part is formed, thus
minimizing the necessary capacity of an additional external heat
exchanger and minimizing the heat loss attributable to peripheral
devices, resulting in improved heat efficiency compared to conventional
commercial hydrogen preparation plants.

[0013]A further object of the present invention is to provide a
cylindrical steam reformer, which can be applied which are small and
require stability, such as hydrogen stations, by designing a reactor
comprising an upper reactor zone, a middle reactor zone, and a lower
reactor zone, which are removably connected so as to enable easy supply
of a catalyst and increase durability.

Technical Solution

[0014]In order to achieve the above objects, the present invention
provides a cylindrical steam reformer having an integrated heat
exchanger, comprising a reactor, the reactor including an upper reactor
zone having an internal heat exchange part, a middle reactor zone
connected to the upper reactor zone and having a combustion part, a steam
generation part, and a reforming part, and a lower reactor zone
constituting the lower surface of the middle reactor zone, in which the
upper reactor zone, the middle reactor zone, and the lower reactor zone
are removably connected, thereby forming the heat transfer path in the
internal heat exchange part of the upper reactor zone and in the middle
reactor zone so as to alleviate the effect of thermal expansion on the
reactor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]The above and other objects, features and advantages of the present
invention will be more clearly understood from the following detailed
description taken in conjunction with the accompanying drawings, in
which:

[0017]FIG. 2 is a schematic view of a steam reformer, according to the
present invention;

[0018]FIG. 3 is a view showing the inner structure of a cylindrical steam
reformer, according to the present invention; and

[0019]FIGS. 4 to 6 are cross-sectional views showing individual parts of
the cylindrical steam reformer, according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0020]Hereinafter, a detailed description will be given of the present
invention, with reference to the appended drawings.

[0021]FIG. 2 schematically shows a steam reformer of the present
invention, and FIG. 3 shows the inner structure of the cylindrical steam
reformer of the present invention.

[0022]FIGS. 4 to 6 show the inner structure of each of an upper reactor
zone, a middle reactor zone, and a lower reactor zone of the steam
reformer, according to the present invention.

[0023]The cylindrical steam reformer according to the present invention is
schematically shown in FIG. 2. As is apparent from this drawing, the
steam reformer of the present invention is characterized by including an
internal heat exchange part, a combustion part, a steam generation part,
and a reforming part in a single reactor. That is, the cylindrical steam
reformer of the present invention is designed to provide the internal
heat exchange part in the reactor so as to minimize the size of the
external heat exchanger necessary for the conventional steam reformer
shown in FIG. 1 and realize minimum heat loss in pipes thereof, and to
improve the flow path of combustion gas so as to enable the use of only a
low-temperature external heat exchanger having a small capacity.

[0024]FIG. 3 is a cross-sectional view showing the structure of the
cylindrical steam reformer having an integrated heat exchanger, according
to the present invention. FIGS. 4 to 6 are cross-sectional views of
individual parts of the steam reformer of FIG. 3. That is, the
cylindrical steam reformer of the present invention is characterized in
that the internal heat exchange part is provided therein, the upper
reactor zone, the middle reactor zone, and the lower reactor zone of the
steam reformer are removably connected in order to enable convenient
assembly or disassembly thereof, and also, filler or a reforming catalyst
to be placed in the flow path of the reformer may be easily supplied and
replaced.

[0025]As shown in the drawings, the cylindrical steam reformer having an
integrated heat exchanger, according to the present invention, comprises
a reactor, which is composed of an upper reactor zone 41 having an
internal heat exchange part 28, a middle reactor zone 42 connected to the
upper reactor zone 41 and having a combustion part, a steam generation
part, and a reforming part, and a lower reactor zone 43 constituting the
lower surface of the middle reactor zone 42. Such individual parts of the
reactor are described with reference to FIGS. 3 and 4 to 6.

[0026]FIG. 4 is a cross-sectional view showing the upper reactor zone of
the steam reformer of the present invention. The upper reactor zone 41
includes two flow paths, one flow path of which functions to transfer
feed/steam, the other flow path of which functions to transfer reformate
formed in the middle reactor zone 42 prior to being externally
discharged. The two flow paths thus formed are positioned adjacent to
each other, and the feed/steam and the reformate flowing in the above
flow paths have different temperatures. Thus, when the feed/steam and the
reformate are passed through the respective flow paths, heat exchange
therebetween takes place, and therefore the two flow paths function as a
heat exchanger. That is, the internal heat exchange part 28 provided in
the upper reactor zone 41 consists of a feed/steam flow path 60 and a
reformate flow path 26.

[0027]The feed/steam flow part includes a feed/steam mixing pipe 14 for
mixing material externally supplied via a material inlet 21 with steam
supplied via a steam inlet 59 from the steam generation part of the
middle reactor zone 42, a feed/steam flow path 60 for transferring the
feed/steam mixed in the feed/steam mixing pipe 14, and a feed/steam
outlet 61 for discharging the feed/steam having exchanged heat with the
reformate through the feed/steam flow path 60 into the reforming part of
the middle reactor zone 42.

[0028]The reformate flow part includes the reformate flow path 26 for
transferring the reformate formed in the reforming part of the middle
reactor zone 42, and a low-temperature reformate outlet 27 for externally
discharging the reformate having exchanged heat with the feed/steam
through the reformate flow path 26.

[0029]As shown in FIGS. 4 and 5, in the heat transfer path of the internal
heat exchange part 28 including the feed/steam flow path 60 and the
reformate flow path 26, the reformate flow path 26 is formed by
connecting the upper reactor zone 41 to the middle reactor zone 42.
Preferably, the above heat transfer path may be designed to have a zigzag
shape by controlling the number of plates constituting it so as to
realize high heat exchange efficiency. Further, metal porous filler is
charged in the internal heat exchange part 28, thereby assuring a maximum
heat transfer area for a minimum volume. The charged filler is preferably
composed of metal having high corrosion resistance, and is in mesh,
fiber, or knit form in order to prevent a pressure drop in the pipe.

[0030]With reference to FIGS. 3 and 5, the middle reactor zone 42 includes
the combustion part, the steam generation part, and the reforming part.

[0031]In the middle reactor zone 42 of the cylindrical steam reformer, the
combustion part, functioning to supply a predetermined amount of heat
required for a reforming reaction, is composed of a burner 2 for burning
air/fuel supplied via an air/fuel inlet 1, a first combustion gas flow
path 51 and a second combustion gas flow path 52 formed for surrounding
the reforming part so as to exchange heat between the combustion gas
produced in the burner 2 and the reforming part, a third combustion gas
flow path 53 for exchanging heat between the combustion gas passed
through the second combustion gas flow path 52 and the steam generation
part, and an exhaust gas outlet 6 for externally discharging the
combustion gas passed through the third combustion gas flow path 53.

[0032]As such, the first combustion gas flow path 51 is positioned between
a combustion pipe 3 and a reforming pipe 54, and the second combustion
gas flow path 52 is positioned between the reforming pipe 54 and a
combustion gas separation pipe 5, in order to surround the reforming pipe
54. In this way, the reforming part is surrounded by the first combustion
gas flow path 51 and the second combustion gas flow path 52, so that heat
exchange between the combustion gas and the reforming part may occur.
Therefore, heat required for the reforming reaction may be supplied from
the combustion gas. As such, the combustion pipe 3 functions to prevent
partial overheating of flame from the burner and to guide the combustion
gas into the first combustion gas flow path 51.

[0033]Further, the combustion gas passed through the second combustion gas
flow path 52 is allowed to pass through the third combustion gas flow
path 53 as a flow path formed by the combustion gas separation pipe 5.
The third combustion gas flow path 53 is defined by a space between the
combustion gas separation pipe 5 and the steam generation pipe 56 so as
to realize heat exchange with the steam generation part. As such, the
combustion gas separation pipe 5 is provided such that the combustion gas
passed through the first combustion gas flow path 51 is dividedly
supplied into two flow paths, that is, the second combustion gas flow
path 52 and the third combustion gas flow path 53. Thereby, heat
generated from the combustion gas is uniformly distributed to the two
flow paths comprising the second combustion gas flow path 52 and the
third combustion gas flow path 53 so as to minimize heat loss, therefore
realizing optimal heat exchange and preventing a drastic drop in the
temperature of the combustion gas. The combustion gas passed through the
third combustion gas flow path 53 is subsequently discharged through the
exhaust gas outlet 6, and thus functions to preheat water flowing to the
inner portion of the reformer in the external heat exchanger.

[0034]In the middle reactor zone 42 of the cylindrical steam reformer of
the present invention, the steam generation part is used to supply steam
to the reformer, and includes a steam inlet 11 for supplying steam in a
combined gas-liquid state or a gaseous state having externally increased
temperature, a steam generation path 12 for increasing the steam supplied
via the steam inlet 11 to a predetermined temperature through heat
exchange with the combustion gas passing through the third combustion gas
flow path 53, and a steam outlet 57 for discharging the steam passed
through the steam generation path 12 to the upper reactor zone 41.

[0035]As such, the steam generation path 12 is defined by a space between
the body 58 of the middle reactor zone 42 and the steam generation pipe
56, and is simply filled with the metal porous filler, thereby assuring
the maximum heat transfer area for the minimum volume. Comparing with a
conventional reactor, around which a heat exchange tube is wound, the
reactor of the present invention is easy to manufacture. The filler is
preferably composed of metal having high corrosion resistance, and is in
mesh, fiber or knit form to prevent a pressure drop in the pipe. More
preferably, useful is stainless steel, which does not cause deformation
or thermal expansion at high temperatures or corrode due to surface
oxidation.

[0036]The steam thus generated is discharged via the steam outlet 57, and
therefore may be supplied to the upper reactor zone 41 through the steam
flow path 13 serving to connect the upper reactor zone 41 to the middle
reactor zone 42. Since the steam flow path 13 is connected to the upper
reactor zone 41 and the middle reactor zone 42 by predetermined flanges,
it may be easily assembled or disassembled.

[0037]In the middle reactor zone 42, the reforming part, functioning to
produce hydrogen from externally supplied feed/steam, includes two flow
paths comprising a high-temperature feed/steam path 23 and a reforming
path 24 formed by the reforming separation pipe 55 that is provided in a
space defined by the reforming pipe 54, and a high-temperature reformate
discharge pipe 25. As such, the high-temperature feed/steam path 23
functions to preheat the low-temperature feed/steam passed through the
internal heat exchange part 28 provided in the upper reactor zone 41 of
the present invention to a predetermined temperature before entering the
reforming path 24 through heat exchange with the second combustion gas
flow path 52 surrounding the reforming pipe 54. The reforming path 24
functions to reform the high-temperature feed/steam passed through the
high-temperature feed/steam path 23 using the reforming catalyst to be
converted into reformate. In such a case, the high-temperature feed/steam
path 23 is also filled with the metal porous filler, as is the steam
generation path 12, thus assuring an effective heat transfer area.

[0038]In the reforming path 24, an Ni-based steam reforming catalyst or an
Ni-based steam reforming catalyst containing at least 0.01 wt % of
precious metal such as Pt or Ru is charged. The diameter of the reforming
catalyst is preferably 1/3 to 1/10 the diameter of the reforming path 24,
in consideration of the pressure drop in the pipe and the reactivity
therein.

[0039]The lower reactor zone 43 of the cylindrical steam reformer of the
present invention is shown in FIG. 6. The lower reactor zone 43,
constituting the lower surface of the middle reactor zone 42, includes
the combustion pipe 3 and the combustion gas separation pipe 5. That is,
the lower reactor zone 43 is connected to the middle reactor zone 42,
thereby forming a predetermined flow path. In this way, the additional
formation of the lower reactor zone 43 results in no interference between
the middle reactor zone 42 and the lower reactor zone 43 upon thermal
expansion caused by the operation of the reformer.

[0040]The combustion pipe 3 and the combustion gas separation pipe 5
defining the heat transfer path are connected to the lower reactor zone
43 and are preferably formed of metal that is easily prepared, or
alternatively may be formed of ceramic material or material having a
thermal transfer coefficient similar to that of the ceramic material in
order to prevent conductive heat transfer. Although the lower reactor
zone 43 is integrated with the combustion pipe 3 and with the combustion
gas separation pipe 5, the present invention is not limited thereto. In
FIG. 3, the reference number 32 designates heat insulating material,
which is used to prevent flame, resulting from combustion in the middle
reactor zone 42, from affecting the other reaction procedures.

[0041]In the present invention, the cylindrical steam reformer having a
heat exchanger integrated therewith is composed of the upper reactor zone
41, the middle reactor zone 42, and the lower reactor zone 43, which are
separately provided or are connected to one another using flanges. In
particular, even upon thermal expansion of metal caused by rapid start-up
operation, the reactor is structured such that the individual reactor
zones do not interfere with one another. Further, the upper reactor zone
41 is designed to be easily removed from the middle reactor zone 42,
whereby the catalyst inlet of the reforming part is opened upon removal
of each reactor zone, thus efficiently supplying the catalyst.

[0042]In addition, the heat transfer path of the middle reactor zone 42 is
effectively arranged so that the heat exchange of the combustion part,
the reforming part, and the steam generation part is efficiently
realized, leading to an optimal heat exchange network.

[0043]The operation of the cylindrical steam reformer having an integrated
heat exchanger of the present invention is described in conjunction with
FIGS. 2 and 3.

[0044]FIG. 3 shows the inner structure of the cylindrical reformer of the
present invention. In the present invention, the operation of the
cylindrical reformer is largely divided into combustion and reforming
processes.

[0045]As shown in FIGS. 2 and 3, in the combustion process, air to be
supplied to the burner 2 of the reactor is preheated in the external heat
exchanger by the reformate discharged via the low-temperature reformate
outlet 27 of the upper reactor zone 41, and is then supplied via the
air/fuel inlet 1. The air thus supplied is burned along with fuel in the
combustion pipe 3 via the burner 2, thus generating heat. The combustion
gas thus generated exchanges heat with the reforming part and the steam
generation part while passing through the first combustion gas flow path
51, the second combustion gas flow path 52, and the third combustion gas
flow path 53. That is, the combustion gas functions to increase the
temperature of the steam passing through the steam generation part while
maintaining the temperature of the reforming part through heat exchange
with the reforming part. Thereafter, the combustion gas is externally
discharged via the combustion exhaust gas outlet 6, thereby completing
the combustion process.

[0046]Referring to FIGS. 2 and 3, the reforming process of the present
invention is described. For the reforming reaction, steam must be
supplied into the reformer of the present invention. To this end, water,
which is externally supplied, is converted into steam in the
low-temperature external heat exchanger, having a small capacity, by heat
of the exhaust gas discharged through the above combustion process, after
which such steam is supplied into the reactor via the steam inlet 11 of
the steam reformer. The steam thus supplied recovers heat of the
combustion gas through heat exchange with the third combustion gas flow
path 53 adjacent to the steam generation path 12 while passing through
the steam generation path 12 and is then supplied into the upper reactor
zone 41 through the steam outlet 57 and the steam flow path 13 and then
through the steam inlet 59 provided in the upper reactor zone 41. The
supplied steam is mixed with the material supplied via the material inlet
21 in the feed/steam mixing pipe 14 and is then transferred via the
feed/steam flow path 60.

[0047]As such, the feed/steam flowing through the feed/steam flow path 60
primarily recovers heat through heat exchange with the reformate flowing
via the reformate flow path 26 adjacent to the feed/steam flow path 60.
Subsequently, the feed/steam are supplied into the middle reactor zone 42
through the feed/steam outlet 61 and then through the low-temperature
feed/steam path 22 acting to connect the upper reactor zone 41 and the
middle reactor zone 42. As such, the low-temperature feed/steam supplied
into the middle reactor zone 42 should be preheated to a temperature
suitable for the reforming reaction before the reforming reaction occurs.
The preheating process is accomplished in a manner such that the
low-temperature feed/steam exchange heat with the second combustion gas
flow path 52 adjacent to the high-temperature feed/steam path 23 while
passing through the high-temperature feed/steam path 23, thereby
secondarily recovering heat from the combustion gas. Then, the feed/steam
are supplied into the reforming path 24 to undergo the reforming reaction
in the presence of the reforming catalyst. After the reforming reaction,
the feed/steam are converted into reformate comprising hydrogen, carbon
monoxide, carbon dioxide, unconverted hydrocarbon feed, and excess water.

[0048]The reformate thus obtained is transferred to the upper reactor zone
41 via the high-temperature reformate discharge pipe 25, and is then
discharged via the low-temperature reformate outlet 27 via the reformate
flow path 26. As such, the reformate flow path 26 is adjacent to the
feed/steam flow path 60, and thus heat may be supplied to the feed/steam
through heat exchange therebetween. The reformate discharged through the
low-temperature reformate outlet 27 is supplied into the water-gas shift
reactor through the additional external heat exchanger, thereby achieving
the reforming process of the present invention.

[0049]In some cases, the amount of fossil fuel for the combustion can be
reduced by using stak off-gas or PSA off-gas as fuel for burner. During
the initial heating-up procedure, the use of the fossil as fuel for
burner is inevitable. However, once the reformer starts to steadily
produce hydrogen in normal operation condition, the reformate can be
delivered into fuel cell stack, and the stack starts to generate
electricity by using hydrogen included in the reformate. The gas stream
evolved from fuel cell stack after consuming appropriate amount of
hydrogen for generating electricity, so called, stack-off gas, still
contains some extent of hydrogen, carbon monoxide, carbon dioxide, and
moisture and can be recycled into burner and used as fuel for the
reformer. For another instance, the reformate from reformer could be
purified by using PSA (pressure swing adsorption) equipment in order to
produce hydrogen in high purity, and the remaining gas (PSA off-gas) is
recycled and used as a fuel for burner, and consequently, it can increase
the total heat efficiency.

INDUSTRIAL APPLICABILITY

[0050]As described hereinbefore, the present invention provides a
cylindrical steam reformer having an integrated heat exchanger, which can
continuously supply hydrogen to fuel cell systems or fuel cell vehicles
requiring hydrogen by reducing the size of a hydrogen generator, typical
of a conventional large plant, and then applying it to fuel cells or
hydrogen stations. According to the present invention, the cylindrical
steam reformer comprises a reforming part, a combustion part, an internal
heat exchange part, and a steam generation part, which are integrally
manufactured into a single reactor, thus forming an optimal heat exchange
network leading to optimal performance of the individual parts. Thereby,
heat loss is minimized and optimal heat exchange efficiency is realized.
In addition, the steam reformer of the present invention is designed to
simplify fluid flow so as to minimize stagnant portions and also to have
high efficiency, stability and durability, in consideration of the
expansion and contraction of the material of the high-temperature
reactor.

[0051]In the case where the steam reformer of the present invention is
mounted in a space which has a small foot-print and requires safe and
stabile operation, such as a hydrogen station, heat exchange efficiency
is maximized and thus total heat efficiency increases, resulting in
decreased hydrogen preparation cost. Further, a sufficiently efficient
thermal network can be realized even using a low-temperature external
heat exchanger having a small capacity while minimizing the capacity of
an external heat exchanger having a limited size. Thereby, additional
material problems can be overcome, therefore improving the commercial
usability of the hydrogen station.

[0052]Although the preferred embodiment of the present invention has been
disclosed for illustrative purposes, those skilled in the art will
appreciate that various modifications, additions and substitutions are
possible, without departing from the scope and spirit of the invention as
disclosed in the accompanying claims.

Patent applications by Il Su Kim, Daejeon KR

Patent applications by Jin Hong Kim, Daejeon KR

Patent applications by Keun Seob Choi, Daejeon KR

Patent applications by Young Seek Yoon, Daejeon KR

Patent applications in class Tubular stages in single reaction chamber

Patent applications in all subclasses Tubular stages in single reaction chamber